Workpieces can pass through solenoidal type induction coils to induction weld or heat the workpieces. Coils of a fixed geometry can efficiently weld or heat only workpieces of a limited range of dimensions.
It is one object of the present invention to provide apparatus and method for electric induction welding or heating of workpieces passing through a solenoidal type coil so that when a dimension of the workpiece changes, the welding or heating process can continue at normal or reduced process line speed without interruption of electric power to the solenoidal induction coil and flow of a cooling medium to the solenoidal coil.